Method of piston ring manufacture



Oct. 23, 1934. t R GROVER 1,977,910

METHOD OF PISTON RING MANUFACTURE 4 Original Filed Feb. 28. 1951 attornegs Patented Oct. 23, 1934 Ray Grover, Milwaukee, Wis v Original application February 28, 1931, Serial No.

519,049, now PatentNo. 1,911,755,

dated May 30, 1933. Divided and this application January 22, 1932, Serial No. 588,097

2 Claims. (01. 29-156153) This invention relates to improvements in methods of piston ring manufacture. The present application is a division of my application Serial No. 519,049, entitled Packing rings and methods of manufacture thereof, filed February 28,1931

(Pat. No. 1,911,755 May 30, 1933).

It is the object of the invention to provide' a novel and economical method of manufacturing, a piston ring which will prevent stoppage of oil transfer past a piston. It is proposed that the ring have a peculiar peripheral contour in cross section, the contour being determined in general by considerations relating to the effective sealing of the piston against oil displacement and. being determined in some particular respects by the convenient application of the manufacturing method here disclosed.

The peripheral conformation of the ring is closely connected with the desired process of 0 manufacture, whereby great economies are effected in production and desired accuracy of result is obtained notwithstanding the use of quantity production methods.

In the drawing:

Figure 1 is a large scale view showing a cylinder in section and a piston and its rings in elevation, with portions of the rings and piston wall broken away to an axial section.

Figure 2 is a fragmentary detail view illustrating a step in the process of manufacture of my improved ring, the rings being illustrated in side elevation between a head and tail stock, a special set of forming tools being also illustrated in side elevation. Figure 3 is an end elevation of the milling tool set shown in Figure 2.

Like parts are identified by the same reference characters throughout the several views. I

The piston 5, operating in cylinder 6, is pro 4 vided'with packing rings at 7 which may be of ring, preferably made by the special method herein disclosed, and having a peculiar peripheral conformation and a peculiar relation to the piston for the purposes of this invention.

It will be noted that rings 7 are fitted closely to their grooves 9. In A; inch to inch piston rings it is customary to fit the ring to its groove with an axial clearance averaging one onethousandth of an inch and with a maximum of two one-thousandths of an inch. In accordance with my present invention, the ring 8 has a substantially greater axial clearance in its groove 10, which for rings of A; to inch in transversemeasurements should exceed three oneany desired construction. The ring 8 'is' an oil c1; thousandths of an inch and preferably approximate five one-thousandths of an inch. The groove 10 is drained by a duct 11 to the interior of the piston, as is common wherever oil rings are used. In'accordance with the present inven- .0;. tion, however, thisdrain does not merely conduct away by gravity the oil collected by the ring but servesasan outlet for lubricant which is actually displaced by the ring, which acts as a displacement pump during the operation of the piston by virtue of its peculiar conformation and the clearance aforesaid. 7 I

It will be understood that the amount of clearance specified is subject to variation according to the kind of lubricant used and other factors -0;. affecting capillary attraction of the lubricant for the ring, the piston, and the cylinder wall, as will hereafter be explained.

The inner peripheral surface 15 of the-ring 8 preferably is spaced conventionally tothe bottom of the piston groove 10. The outer surface of the ring, instead of being in full peripheral contact with the cylinder wall, is preferably reduced in area by marginal peripheral cuts which may divide the periphery of thering into three parts. One part of the area is represented by the central land 16 and one part by each of theannular notches adjacent thereto. g g

The notchesare soformed that the ring has annular cylindrical bottom wallsl'l and 18, respectively, which are 'coaxial withj the ring and of substantially like radius. ie surface leading from wall 1'7 to the outer periphery of land-16 is an inclined or bevelled surface 20, while the surface leading from wall 18 to the periphery of the land 16 is a right angle shoulder 21.

As the piston 5 moves upwardly in cylinder 6 its rings wipe the wall of the cylinder, and any excess of oil which has managedtoreach the wall of the cylinder above the oil ring Swill tend to" accumulate above bevelled surface: 20 and above the oil ring 8 ,--v vhich, because of its relatively reat: clearance in the ringgrooveIO and its ma tionagainst the cylindrical wall, will'have positioned itself at the bottom of its groove. The spacing between the ring and the groove should be such as to leave a space between the ends of the ring and the piston exceeding that'space which may be bridged by capillary attraction of the lubricant to the surfaces. If the ring has merely the toleranceor clearance ordinarily employed capillary action will retain lubricant between the ends of the ring and the piston walls, and hence there will be no substantial variation in capacity of the oil space. 1 10 ment by the ring of the lubricant-accumulated:

thereabove produces sufficient pressure to enable the lubricant to pass the ring. In any event,

it is a demonstrated fact that the-use of the ring will result in substantially relieving. the

cylinder of lubricant above the ringand delivering all excess lubricant through duct 11.

The sharp angle between right angle surface .21 and the periphery of land 16 functions as"a scraper so that as the piston moves downwardly with the. oil; ring 8 in the top of its. groove excess lubricant is scraped frornthecylinder wall into.

the. lower marginal notch. and the "space below thering which, as above. explained, is in. excess of the spacewhich can be bridged by the type of lubricant employed. Considerable lubricant will beaccumulated in this space as the piston moves downwardly, and upon change of piston direction the cylinder wallfriction upon land 16 causes the ring to tend'to stand stillwhile the-piston moves upwardly against it. Thus, .thering. acts.

like .a displacement pump and expels through duct 11 the lubricant accumulated.

The cylindrical surfaces peripherally notched portions of ring 8 greatly facilitate the preferred process of manufacture, as hereinafter disclosed. V

I Anyenumber of rings are mounted coaxially for rotation between a head 26,-xas illustrated-by the three rings shown in Figure 2. As the head stock and tail stock are rotated the ringblanksare acted on by a cutting tool which maycomprise a-former 27 mounted on shaft 28 and notched to provide a cutting edge at 29. There will be a number of individual form-- ing elements 30 to ,a number exceeding by one the number of rings to be flnished.. These elements may be unitarily. connected, as shown in the forming device 27, if desired. In eachelement the cutting edge 29 has arectilinear-portion 31 parallel to the axis of thecutter shaft 28.

7 and corresponding in axial length to the combined corresponding dimensionsof ringsurfaces l7 and 18. It will be observed that-the cutting edge 31 spans the joint between two. adjacent rings. 1

Immediatelyadjacent the cutting margin 31 is an inclined or beveled cutting margin 32 corre-.-

spond-ing: to thedesired inclination of; margin 20' of the ring. It is unnecessary, because of the fact-that the cutter operates simultaneously on tworings, to govern accurately thelength or the exact positionof the inclinedsurface 32 of the cutter. 7 Y

r1 and 18 of the stock 25 and a tail stock If the upper face of land 16 were beveled all the way to the upper face of the ring it would be necessary that the milling or cutting tool have the apex of its angular cutting surface coincide perfectly with the joint between two adjacent rings. It is the indicated ring contour, having corresponding surfaces 17 and 18 at each end of each ring, that makes it' possible to produce the ring in quantities with cutting elements each of which act simultaneously on two rings as shown.

Tests have demonstrated the fact that the mere substitution ofthe oil ring herein disclosed for one of the packing rings in any piston, having a groove substantially longer than the ring in accordance with the foregoing disclosure, will completelyeliminate waste of oil past such a piston. This ring, has been used not only in internal combustion engines, but :also in air compressors, and it operates to limit the lubricant on the wall of the cylinder to that required for actual piston lubrication, .so that. virtually none. of the lubricant escapes. Themost seriouscasesof oil pumping have been corrected 1 by use. of. one. ring. per offending piston.

I claim:.

1. The method of manufacturing piston rings having raised peripheral lands intermediate the end faces of the rings, each of said lands having oneradial and one slantingmarginal wall, whichmethodconsists in rotating. axially aligned ring blanks and applying a tool to 'two contiguous rings to simultaneously machine marginal portions of said blanks, said .tool-being shapedto. contour the said radial and slanting walls of their respective blanks, whereby theradial wall of one ring as formed by the toolmay comprise a. bul-. wark guide for the tool .to prevent-the crowding, of the toolin the process of cutting the slanting wall of the other ring, said machiningfbeingcontinuedperipherally' of the aligned blanks until. the machined portions are reduced to substantially less diameter than the periphery of. said lands.

2. The method of manufacturingpiston.rings having raised peripheral lands intermediatetheir end faces, each of said lands having one. radial and. one slantingmarginal wall, which method.

consists in the co-axial alignment of .rin'glblanka',

ripherallyof the aligned blanks untilthe machined portions are reducedto' substantially less diameter than the periphery of said lands.

RAX GRoy R. 

